People who need constant oxygen are often prescribed with an oxygen concentrator, sometimes called an oxygen generator. There are two types of oxygen concentrators: home and portable. Home devices are designed to move from room-to-room throughout the house and plug into a wall outlet. They can even be moved outdoors, but require an electricity source to operate.
Regardless of whether or not they are home or portable, all oxygen concentrators work primarily the same way. Simply put, the device takes air from the environment, purifies it, and distributes air with the highest dose of oxygen possible to the user, via a nasal cannula or mask.